Definition of the P0311 code
The P0311 code is stored when the Powertrain Control Module (PCM) detects a misfire in engine cylinder 11. When this happens, the engine malfunction indicator light or MIL (malfunction indicator light) comes on and stays on until the problem is resolved.
What code P0311 means
An ignition error in a vehicle engine is simply a lack of combustion, which has several potential causes. The P0311 code is a means for the PCM to remember the fact that cylinder 11 has failed. Based on this code, the mechanic can determine the cause and appropriate repairs to prevent further cylinder failures in the future.
What causes the P0311 code?
- Since the P0311 code is specific to cylinder 11, all causes and repairs will be related to this cylinder. Some of the problems that can occur with cylinder 11 and its components are.
- Faulty spark plug
- Fuel injector open or short-circuited
- Fuel injector clogged or damaged
- Defective ignition coil
- Bad electrical connection to fuel injector
- Ignition coil wiring open or short-circuited
- Insufficient cylinder pressure
- Incorrect fuel pressure
- Air leakage at intake
What are the symptoms of the P0311 code?
A misfired cylinder does not cause many symptoms, but you may notice that the vehicle vibrates at idle when the ignition is not working. Fuel efficiency can also suffer, as can the car’s performance on the road. A constant symptom, of course, will be an illuminated check engine or MIL light.
How can a mechanic diagnose the P0311 code?
After using an OBD-II scanner to detect the P0311 code, the mechanic will know which cylinder is failing and can take steps to diagnose the problem. One of the first diagnostic steps is to replace the ignition components between cylinder 11 and one of the good cylinders. After replacing the components, the mechanic erases the code and restarts the vehicle to see if the ignition error code has been transferred to the new cylinder. If this is the case, one or more components are the problem and need to be repaired or replaced.
If the component change leads to the same P0311 code, the problem may be a compression problem. The most likely causes are exhaust valve problems or a leaking head gasket. A mechanic will look for coolant leaks or an overheating engine as potential indicators of a head gasket problem.
The most common errors when diagnosing the P0311 code.
Assuming that the problem is the ignition components in cylinder 11 and replacing them before checking with a good cylinder is a common problem. While these components are the most likely cause of the problem, it is best to do a thorough diagnosis and determine exactly what the problem is before drawing (potentially expensive) conclusions.
How serious is the P0311 code?
In some cases, the P0311 code will not be very serious and will only be noticed by an illuminated Check Engine light and a noticeable vibration at idle. However, if a single cylinder problem is left alone, it can become a much larger problem. This is why it is so important to check your vehicle as soon as possible and make the appropriate repairs.
What fixes can repair a P0311 code?
In most cases, a misfiring cylinder can be repaired by replacing some or all of the ignition components, such as
- Spark plug
- Fuel injector
- Ignition coil
- Ignition Coil Wiring
- If the problem is not caused by the ignition components, it can probably be corrected by repairing or replacing a leaking cylinder head gasket or exhaust valve.
Additional notes to consider code P0311
If the misfire on cylinder 11 does not affect vehicle performance, you may be tempted to skip this code. Note, however, that the vehicle cannot pass OBD-II emissions tests if Check Engine Light or MIL Light is on.
